Adherence to HIV antiretroviral therapy (ART) is closely associated with viral suppression, drug resistance and disease progression. Although near perfect adherence is needed for reliable viral suppression, average adherence to HIV antiretroviral therapy is under 70%. Accurate assessment of adherence is the first step in improving adherence because it identifies patients in need of more intensive intervention and monitoring. Patient self-report is the least costly and most practical method for assessing adherence in routine practice, but has poor sensitivity at detecting nonadherence. On the other hand, unannounced home pill counts are accurate and sensitive to the detection of nonadherence, but are not feasible in routine clinical practice because of their high cost and labor demands. Electronic medication monitors designed for clinical practice deliver objective, real-time adherence monitoring at a reasonable cost. Data from monitors are associated with viral suppression and the development of resistance. The most commonly used device, MEMS Caps, has several limitations however, including the number of medications it holds, cumbersome reporting functions, and price. Lacking a valid, practical, and inexpensive method of adherence assessment, providers rely on informal and unsystematic assessments of adherence that are often no better than chance. Understanding these challenges, InforMedix has developed the Med-eMonitor System, an affordable and easy-to-use electronic adherence measurement device coupled with a Web-enabled device programming and reporting system. We propose a 3-month observational study to test the feasibility and validity of the Med-eMonitor in people taking ART (N=50). We will assess the feasibility of the devices using self-reported likeability and usability surveys, and device-related process measures. We will assess validity with concurrent unannounced home pill counts and viral load monitoring. Our specific aims are as follows: Specific Aim 1: Examine the feasibility of the Med-eMonitor device for use by HIV positive people living in the community. We will document the feasibility of the device's use using process variables (i.e., drop out rates, missing data), and qualitative usability and likeability data derived from one-on-one interviews. Specific Aim 2: Measure the validity of the Med-eMonitor device's measure of medication adherence using unannounced pill counts and HIV viral load. We will estimate the device's measurement validity via comparisons with viral load suppression and unannounced, home-based pill counts. If valid, Med-eMonitor may accurately measure ART adherence, thus improving HIV disease outcomes. [unreadable] [unreadable] [unreadable]